Systems that provide for sustained release of chemical compounds are useful in a host of contexts. Of particular interest herein are sustained release systems for providing gradual release of a beneficial pharmaceutical or other agent in the aqueous environment of the human body, specifically the mouth. The difficulty in achieving optimal sustained release systems for extended delivery of a beneficial agent in the mouth is that most such systems, e.g., lozenges, last for only a matter of minutes. For example, halitosis—commonly known as bad breath—is often treated with flavored lozenges and gums. Flavored lozenges and gums have also been used to deliver a pharmacologically active agent. For example, nicotine gums for assisting in smoking cessation are known and have been commercially available for some time. Most flavored lozenges, however, dissolve in several minutes or less, and therefore provide only a very short-term effect. Similarly, most gums tend to release substantially all of a beneficial agent (e.g., a flavoring agent or a pharmacologically active agent such as nicotine) in well under half an hour. Dosage forms for sustained release of beneficial agents in the mouth can be problematic in other respects as well. For example, commercially available zinc lozenges for treating the common cold tend to dissolve or degrade in well under 15 minutes, and, to the best of applicants' knowledge, no zinc lozenge has been disclosed as providing sustained release of zinc for over 40 minutes. Ideally, effective antiviral pharmacotherapy would involve a far longer time period during which the active agent is released from the lozenge.
Various materials and methods are used in the preparation of sustained release delivery systems. Often, sustained release is achieved by coating a dosage form such as a tablet or drug-containing core with a layer of a polymeric material that gradually hydrolyzes or erodes to release the beneficial agent within. Sustained release has also been achieved by granulating tablet materials with such a polymeric material. For instance, pharmaceutical grade ETHOCEL® brand ethylcellulose, available from the Dow Chemical Company (Midland, Mich.), is primarily used in the pharmaceutical industry to coat tablets and capsules, as granulation binders, and as binders in the direct compression of tablets. To date, however, neither ethylcellulose nor any other water-insoluble hydrophilic polymer as been used to provide a sustained release flavored dosage form as now disclosed.
There is, accordingly, a need in the art for a dosage form and method that achieve release of a beneficial agent in an aqueous environment, particularly in the mouth, over a sustained time period, preferably on the order of an hour or more. An ideal system would be a pleasantly flavored lozenge or gum that is comfortable to retain in the mouth for an extended period of time, provides effecting taste-masking of any bitter-tasting or otherwise unpleasant-tasting beneficial agents or excipients, can be easily manufactured, and can be used to deliver a wide variety of beneficial agents in the mouth. In addition, it would be optimal if the components of the composition could be varied only slightly to provide significant changes in properties and methods of use, e.g., to provide a non-adhesive lozenge or a relatively tacky dosage form that can adhere to the gum or teeth.